Solar dishes popping up in US deserts

Next-generation solar dishes called SunCatchers are popping up like desert cactus flowers, with a light and structurally efficient design that can be manufactured on an automotive-type assembly line. The concentrating solar power systems by Stirling Energy Systems of Scottsdale, Ariz., have been installed at Sandia National Laboratories in Albuquerque, N.M., as part of a pilot power-generating facility. The company is gearing up for several commercial installations as well.

Each 11.6-m dish of the Sun Catcher is made up of 40 mirror facets, which are manufactured on automotive-type assembly lines.The project at Sandia National Labs previously had six rectilinear SunCatchers; the recent addition of four redesigned SunCatchers took the total amount of usable energy produced from 150 to 250 kW. The collector’s parabolic shape uses half the number of mirrors as the rectilinear version (40 as opposed to 82). It works by reflecting the sun’s energy off the mirrors onto a point, which concentrates the energy 1300 times before it enters a power conversion unit. A Stirling engine inside the unit uses that intense heat to drive a 25-kW generator.

The mirror facets (including rib supports, metal substrate and mirrors) are manufactured by Tower Automotive of Livonia, Mich., which is moving into the solar industry partly because the mechanical support structure for the mirror facets is similar to that for automobile hoods. During the manufacture of a mirror facet, the rib supports and metal substrate are stamped out, just as they are when a hood is made. In conjunction with Stirling Energy Systems, Tower Automotive devised a technique for assembling the mirrors into a parabolic shape.

Tessera Solar of Houston is a sister company to Stirling Energy Systems and is responsible for the deployment and energy generation of the SunCatcher dish system. The first commercial plant utilizing the technology is under construction in Peoria, Ariz., where 60 SunCatchers will provide 1.5 MW of power to the grid. Tessera Solar also has plans for projects in California and Texas, which will bring the number of SunCatchers growing in US deserts to more than 60,000 by the end of 2014.